Variable fill fluid coupling

ABSTRACT

In variable fill fluid couplings of the type disclosed herein, a driving impeller and a driven runner are coupled for joint rotation by means of a liquid medium in an active liquid chamber formed by the rotating members. The driving impeller is driven at a constant speed by an electric motor, and the active liquid chamber is both continuously bled and continuously fed at rates that can be changed to vary the level of fill of liquid therein. The percentage of liquid fill in the active liquid chamber determines the degree of slip of the runner relative to the impeller which, in turn, determines the speed of the runner under a given load and hence the speed of the output shaft. Such couplings are particularly useful for driving centrifugal pumps at variable rates to maintain a constant pressure in a line on the discharge side of the pump that is subject to a variable demand. To control the rate of fill in a manner that responds rapidly to changes in demand, charging liquid is fed from a source through an orifice which directs the charging liquid into a flowing stream aligned to enter the mouth of the active liquid chanber. A splitter assembly is pivotally mounted to swing in a plane that extends transversely of the flowing stream between the orifice and the mouth of the chamber in order to deflect a portion of the flowing stream away from the mouth. Control means responsive to pressure at the discharge side of the pump causes the splitter assembly to pivot in order to vary the quantity of liquid entering the mouth of an active liquid chamber.

Jan. 28, 1975,

bers. The driving impeller is driven at a constant speed VARIABLE FILL FLUID COUPLIN( by an electric motor. and the active liquid chamber is both continuously bled and continuously fed at rates that can bechanged to vary the level of fill of liquid Inventor: Philip R. Bunnelle, Santa Clara,

Calif.

[73] Assigneel FMC p r n. 51m 1050, Cflliftherein. The percentage of liquid flll in the active liq- Filed: Jan. 23, I974 uid chamber determines the degree of slip of the runner relative lo the impeller which. in turn, determines the speed of the runner under a given load and hence [2]] Appl. No.: 435,799

the speed of the output shaft. Such couplings are particularly useful for driving centrifugal pumps at variable rates to maintain a constant pressure in a line on the discharge side of the pump that is subject to a variable demand. To control the rate of fill in a manner 00 0 (OHS/0 B3 B w sm 5 W mm mmh

that responds rapidly to changes in demand, charging References Cited isflfled gom a soliiirceidthirnotugha a?l :Ai/iIfiCC :vhich S UNITED STATES PATENTS irec s e argmg qu L ng ream aligned to-enter the mouth of the active liquid chan- 2,785,533 Thompson 60/359 X her. A splitter assembly is pivotally mounted to swing in a plane that extends transversely of the flowing stream between the orifice and the mouth of the chamber in order todeflcct a portion of the flowing stream away from the mouth. Control means respon- 00 5 a 3 r nu a 6 w H d m E W m W a. M mm m e m wK m S k d R n T n a U gm 8 d r H 5 r r w l I .HH 0 "6 l mam o. E 3 M y wM 0 r l mOE 2 H 3 PAC sive to pressure at the discharge side of the pump causes the splitter assembly to pivot in order to vary the quantity of liquid entering the mouth of an active liquid chamber.

[57] ABSTRACT In variable fill fluid couplings of the type disclosed herein, a driving impeller and a driven runner are coupled for JOmt rotation by means of a liquid medium in 9 Chin, 5 Drawing Figures an active liquid chamber formed by the rotating memas g c.

. pmmmm'zalszs sum 1 or 4 PATENTED JANE 8 I975 SHEET 20F 4 PATENTEU JAN28|975 SHEET 0F 4 VARIABLE FILL FLUID COUPLING BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a variable fill fluid coupling, and more specifically, it pertains to an improvement in the means for achieving variable filling of such a coupling with charging liquid.

2. Description of the Prior Art In variable fill type fluid couplings of the type disclosed herein, liquid constantly bleeds from an active liquid working chamber in the coupling and charging liquid is constantly added thereto. A driving impeller and a driven runner are rotatably mounted in the working chamber and are coupled for joint rotation by the active liquid therein. Either the rate of bleeding of liquid from the active liquid chamber or the rate of adding liquid thereto can be varied to stabilize the level of fill in the chamber at a level which will provide a predetermined speed for the runner, or driven element of the coupling, under a given load.

In couplings of the type which includes the present invention, the bleed orifices of the active liquid chamber are of a fixed size, and the rate of filling, or charging, of the active liquid chamber is varied. This raises or lowers the level of fill in the chamber and thereby determines the degree of slip of the runner relative to the impeller. When the impeller is driven at a constant speed, the aforesaid variation in charging rate determines the speed of the runner and hence the speed of the output shaft of the coupling.

Such couplings are particularly useful for driving centrifugal pumps that serve as booster-pumps for water systems servicing apartment houses and other buildings. Other applications may be found in municipal water systems and in commercial industrial processes. These pumps may be employed as auxiliary boosters where available water pressure is not always sufficient to meet the demand. Such couplings can also be used to provide aconstant speed output from a variable speed input using controls known in the art.

In my prior US. Pat. No. 3,210,940 a variable fill fluid coupling is disclosed wherein the active liquid working chamber of the coupling is charged by a constant displacement pump which is driven from the impeller shaft. The pump supplies the charging liquid from a sump at the bottom of the housing that encompasses the coupling. A relatively movable charging nozzle and a charging stream splitter assembly are provided, the relative positioning of which determines the proportion of the charging liquid from the pump which will enter the working chamber of the coupling with the balance of the charging liquid being bypassed and re turned to the sump. Suitable control means are provided to determine the relative position of the nozzle and the splitter assembly. There is a certain amount of delay, however, in responding to changes in demand due to the required movement of the charging nozzle or movement of the splitter assembly within the coupling. Furthermore, after the charging liquid has been divided, it must travel to the working chamber of the fluid coupling and develop pressure equivalent to that of the fluid therein acted upon by centrifugal force to alter the percent of fill of the coupling. In large coupling, where a large amount of charging liquid is required, the reaction forces on the splitter assembly can SUMMARY OF THE INVENTION Within the housing of a variable fill type liquid coupling, a driving impeller and a driven runner are rotatably mounted in liquid coupling relationship. An active liquid chamber defined between the impeller and runner has a mouth for receiving charging liquid and a rat dially extending discharge passage allowing it to be bled centrifugally. An orifice positioned adjacent the chamber mouth transforms charging liquid received from a liquid source into a flowing stream aligned to enter the mouth obliquely. A splitter arm is pivotally mounted to swing in a plane that extends across the path of the flowing stream to deflect portions of the stream away from the mouth. Control means are utilized to pivot the splitter arm to vary the quantity of liquid entering the mouth of the active liquid chamber.

With the liquid charging assembly of the present invention there is a reduction in the dead time between a change in the control setting and the resultant response ofthe runner, and hence the stability of the coupling is better than with prior art couplingsof the same general type. Furthermore, the design is such that reaction forces on the splitter are reduced to a minimum so that high powered control mechanisms will not be required even in large scale installations where a large flow of charging liquid is required.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a side elevation view of a fluid coupling embodying the present invention showing the drive motor for the coupling and a centrifugal pump connected to be driven by the coupling.

FIG. 2 is a longitudinal section of the coupling shown in FIG. 1.

FIG. 3 is an enlarged section taken on the line 3-3 of FIG. 2.

FIG. 4 is an enlarged section taken on the line 4-4 of FIG. 2.

FIG. 5 is a perspective view ofa fragment of the splitter assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to FIG. I, a variable fill liquid coupling 10, embodying the present invention, is provided with a constant speed drive motor M and has a conventional centrifugal pump P mounted on its output shaft to form a hydraulic system providing variable flow at constant pressure. The pumpis provided with a liquid inlet line A through which liquid is fed to the pump impeller (not shown), and the impeller discharges liquid under a selected pressure to a liquid discharge line D. A pressure control line PC connects the discharge line D with the liquid coupling 10 and a pressure control gauge PG is mounted in the control line.

The variable fill liquid coupling 10 is proivded with a main housing 12 to which a drive motor mounting plate 13 is bolted forming one end of the housing and to which a pump mounting plate 14 is bolted forming the opposite end of the housing. A cover plate 15 is secured to the top of the housing.

Looking now at FIG. 2, it will be seen that the housing 12 includes a bearing seat 17 which projects inwardly of the drive motor mounting plate 13. Com-' bined radial and thrust bearings 18 and 19 are fitted within the bearing seat for rotatably mounting an input.

shaft 20. The constant speed drive motor M, shown in FIG. 1, has been removed from the drive motor mounting plate and input shaft as shown in FIG. 2, but it will be understood that the drive shaft of the motor M is arranged to be keyed to the end of the input shaft where a keyway 21 is provided.

A hub 23 is mounted on the end of input shaft within the main body of the housing 12. A key 24 locks the hub in position for rotation with the shaft, and a snap ring 25 holds the key in a fixed longitudinal position upon the shaft. Set screws 26 are provided to lock the hub on the shaft. Circumferentially mounted on the central portion of the hub is a sprocket 27 for providing a driving connection with a circulating pump 51 for the charging liquid. A driving impeller 28 is bolted to the end of the hub 23 and thus is adapted to be continuously driven by the motor M.

An annular cover, or shroud, 30 is attached to the driving impeller 28 by a plurality of screws 31 (one only being shown in FIG. 2). An active liquid chamber 32 is formed in the annular space between the radially extending inner face 28a driving impeller and the radially extending inner face 30a of the shroud. Removable bleed orifice screws 33 (one only being shown in FIG. 2) are provided at the outer edge of the shroud to constantly bleed liquid from the active liquid chamber. These screws are provided with metered bores 34, and the screws are removable to facilitate replacement with screws having bores of a different diameter to obtain a desired bleeding rate from the active liquid chamber of the coupling.

Also mounted within the active liquid chamber 32 is the driven runner 36 in liquid coupling relationship with the impeller 28 and shroud 30. The driven runner is fastened by means of bolts to a hub 37 keyed to one end of an output shaft 38 and held in place axially thereon by a lock nut 39 and washer 39a. The driven runner is provided with a plurality of radially extending blades 40 which are uniformly spaced about the axis of the output shaft. The driving impeller 28 has corresponding blades 41, and the shroud 30 is provided with sets of narrow blades 42 uniformly spaced about the drive axis and extendiing in the space between the inner face 30a of the shroud and the outer wall of the runner. These blades cooperate to maintain the driven runner in liquid coupling relationship with the driving impeller. They also act upon the charging liquid which enters the active liquid chamber and serve to bring it quickly up to the rotational speed of the shroud, i.e., the input speed.

The central portion of output shaft 38 is journaled within bearings 44 and 45 fitted within a bearing seat 46 that projects inwardly from the pump mounting plate 14. A bearing cap 47 is bolted to the external face of the pump mounting plate, and a dirt seal 48 is press fitted into the bearing cap in sealing relationship with the output shaft 38 to prevent dirt from reaching the bearings. The drive shaft of centrifugal discharge pump P, shown in FIG. 1, is arranged to be connected with the projecting end of the output shaft 38 which is provided with a keyway 49 (FIG. 2) for this purpose.

The circulating pump 51, which transfers the charging liquid from the housing 12 to the active liquid chamber 32, has a mounting bracket 52 that is bolted to a platform 53 in the bottom of the housing. A drive shaft 54 extends outward from the pump body and has a sprocket 55 mounted thereon. A drive chain 56 is trained about sprocket 27 on hub 23 and the sprocket 55 to drive the pump from the input shaft 20.

Attached to the inlet side of circulating pump 51 is an elbow 58 having a nipple 59 connected thereto. The nipple is directed downwardly towards the bottom of the main housing 12 which forms a charging liquid sump. A fitting 60 connected to the discharge side of the circulating pump is attached by a hose 61 to a fitting 62 mounted in a protuberance 53 on the upper side of the bearing seat 46 surrounding the output shaft 38. An inclined nozzle passage 64 within the protuberance extends from an opening in the fitting to an elliptically shaped discharge orifice 65 (FIG. 4).

The shroud 30 is provided with an inner annular edge 3012 which is radially spaced from the output shaft 38, and the annular opening therebetween in a plane perpendicular to the axis of rotation of the output shaft forms a mouth 67 for the active liquid chamber 32. Discharge orifice 65 is located adjacent the mouth and is aligned to direct a flowing stream of liquid therein. The stream is angled so that its major component is parallel to the plane of the mouth. Thus, the stream is directed into the active liquid chamber toward the outer circumferential portion thereof where it is needed to change the level of fill in the coupling, and it will be appreciated that the response time is minimized. Also, the stream is brought into the active liquid chamber in a position to be intercepted by the rotating blades 42 which act to quickly bring the charging fluid up to the rotative speed of the liquid in the chamber. It is to be noted that the stream of liquid projected from the discharge orifice 65, as shown in phantom line in FIG. 4, has an elliptical cross section 68 in the vertical plane of mouth 67. The centerline of the flowing stream is offset from the axis of rotation of shaft 38 and should preferably be in the direction of rotation of the driven runner (as indicated in FIG. 4) so that the stream will enter the active liquid with a component of motion in the direction of rotation of the chamber.

It will be noted that circulating pump 51 is driven from input shaft 20 which, in turn, is driven by the constant speed drive motor M. Thus, the stream of liquid flowing from discharge orifice 65 has a constant quantity of flow. In order to vary the output of the coupling it is necessary to vary the quantity of liquid in the active liquid chamber 32 to regulate the speed at which the driven runner 36 is driven. Since the metered bores 34 of bleed orifice screws 33 have a fixed size during operation, the quantity of liquid in the active liquid chamber cannot be varied substantially by modification of the liquid flow discharged from the chamber. Therefore, it is necessary to control the quantity of liquid entering the mouth 67 to regulate the liquid fill of the active liquid chamber.

A splitter assembly 70 is provided for controlling the quantity of liquid passing into mouth 67. The assembly is arranged to be pivotally mounted within a U-shaped pivot block 71 fastened to the interior surface of cover plate 15. The splitter assembly has a lever arm 72 that fits between the two legs of the pivot block, as shown in FIG. 2, and a pin 73 is rotatably mounted in bearings in the pivot block legs and is rigidly fitted within the end of the lever arm. A set screw 74, shown in FIG. 3, locks the pin to the lever arm so that the lever arm will rotate within the pivot block about the axis of tehe pin.

Depending perpendicularly from lever arm 72 is a mounting leg 76 having a splitter vane 77 of angular shape attached thereto. A leg 78 of the splitter vane is aligned in a plane which includes the pivotal axis of pin 73 while another vane leg 79 extends'perpendicularly thereto. The splitter vane extends downward to a level below discharge orifice 65 and is arranged to swing transversely between the orifice 65 and mouth 67 (when lever arm 72 is pivoted in pivot block 71) to block a portion of the flowing stream of liquid from nozzle passage 64. It will be noted that the flowing stream of liquid makes a very shallow angle with the splitter vane so that only a minimum amount of reaction force is provided by the vane.

To control the movement of the splitter assembly 70, the pressure control line PC from the discharge end of pump P is connected to a bellows assembly 80 mounted atop the cover plate 15. The bellows assembly includes a conventional bellows against which the fluid in control line PC is directed. A plunger 82 is fixed to the bellows and projects downwardly therefrom into a conical cavity 83 (FIG. 5) in the upper surface of lever arm 72. As pressure increasees on the upper side of the bellows due to an increase in pumping pressure, the plunger is projected downward engaging the lever arm and causing the splitter assembly 70 to pivot about the axis of pin 73 in the pivot block 71. As pressure on the upper side of the bellows is reduced, the plunger retracts and allows lever arm 72 to move upwardly under the urging of a compression spring 87. An adjusting screw 84 extends through an opening in cover plate and through an opening in lever arm 72. A knob 85 for manual actuation is fixed to the upper end of the adjusting screw while the opposite end of the adjusting screw is threaded to receive a stop plate 86. The compression spring 87 fits between the stop plate and the lever arm to urge the lever arm upwardly. A guide rod 88 is threadably fitted into cover plate 15 and depends therefrom. The guide rod is adapted to be loosely received within a notch in stop plate 86 to prevent the stop plate from rotating upon rotation of the adjusting screw. Thus, it will be seen that as the adjusting screw is rotated to move stop plate 86 upward, the compression spring is compressed to provide a greater reaction force upon the lever arm. As stop plate 86 is lowered by adjustment of the adjusting screw in the opposite direction, the reaction force of the compression spring will be reduced. A spacer 90 is fitted upon guide rod 88 adjacent cover plate 15 to support a washer 91 in a position below the end of lever arm 72 where the washer is locked in place by a lock nut 92. The edge of the washer 91 projecting under the lever arm limits the downward movement of the lever arm.

It is to be noted that the stream of charging liquid does not apply a component of force to the splitter assembly 70 in the direction of the applied control force through plunger 82 (other than a minor force component introduced by the drag of the charging fluid on the splitter vane 77). Thus, the forces introduced by the charging stream will not adversely affect the control forces, and accurate and reliable control is assured. This permits the use of control mechanisms with low output forces and allows the coupling of the present invention to be controlled by conventional commercial control devices without necessitating expensive additional force-multiplying mechanisms.

A heat exchanger 94, shown in FIG. 3, is fixed within the main housing 12 for cooling the liquid in the lower sump portion of the main housing.

In operation of the coupling of the presentinvention, the knob 85 is first adjusted to set the compression spring 87 for maintaining a given operating pressure in discharge line D. When drive motor M is started, the fill level of the coupling will usually be too small, and the output pressure of the centrifugal pump will be low due to excessive slip between the runner 36 and impeller 28. Under these conditions, compression spring 87 will move lever arm 72 upward until it contacts cover plate 15 and the splitter assembly does not obstruct the stream of liquid flowing from discharge orifice 65 into mouth 67 of active liquid chamber 32.

Liquid entering mouth 67 impinges upon driven runner 36 and is deflected between the driven runner and the shroud 30 towards the outer circumferential portion of the active liquid chamber 32 where it is further urged by centrifugal force. The rate of charging under these circumstances will exceed the rate of bleed of charging liquid from bleed orifice screws 33 so that the fill level of the coupling will increase rapidly. The increased fill level reduces the slip between the impeller 28 and runner 36 which increases the speed of the centrifugal pump P so that the discharge pressure in line D quickly rises. When the discharge pressure, which acts upon bellows assembly 80, exceeds the given operating pressure for which knob 85 was set, plunger 82 is deflected downwardly, pivoting lever arm 72 against the force of compression spring 87, and moving the splitter vane 77 to partially block the stream of liquid flowing between orifice 65 and mouth 67. This movement of the splitter vane (in the clockwise direction as shown in FIG. 4) will decrease the amount of charging liquid entering the mouth and increase the amount of liquid deflected downwardly towards the bottom of main housing 12. Since the quantity of charging liquid entering the mouth is reduced and the bleed rate through orifice screws 33 is essentially unchanged, the fill level in the active liquid chamber will be lowered. This allows more slip to occur between the impeller and runner with a corresponding decrease in the driving speed of the centrifugal pump P. The discharge pressure will drop correspondingly until a stable condition is obtained.

It is to be noted that the bleed rate of liquid out of the bleed orifice screws 33 will increase (due to a greater head of liquid) as the level of fill in the active liquid chamber increases and will decrease with a reduction in the level of fill. Such changes in the bleed rate compensate to some extent for changes in the rate of fill and have a tendency to stabilize the operation of the splitter assembly 70. The splitter assembly will assume a different angular position for each level of fill to be maintained in the active liquid chamber 32.

Since the orifice 65 is located directly adjacent to the mouth 67 and the splitter assembly is pivotally mounted to swing in a plane transversely of the flowing stream of liquid between the orifice and mouth, the fluid coupling 10 responds rapidly to changes in pressure in discharge line D. The direct flow from the orifice into the mouth minimizes the response time and is angled to rapidly charge the active liquid chamber. Mounting of the splitter assembly to pivot about an axis that extends in substantially the same vertical plane as the centerline off the flowing stream minimizes forces that tend to override the control force and thus impair the accuracy of the control means. The structural shape of the splitter vane and the specific arrangement of the splitter assembly, pressure responsive plunger, compression spring, adjusting screw, and stop plate enable rapid adjustment to be made in the output speed of the fluid coupling in response to changes in pressure in the discharge line D.

Although the best mode contemplated for carrying out the present invention has been herein shown and described, it will be apparent that modification and variation may be made without departing from what is regarded to be the subject matter of the invention.

What is claimed is:

1. In a variable fill type liquid coupling having a housing, a driving impeller rotatably mounted in said housing, a driven runner rotatably mounted within said housing in liquid coupling relation with said impeller, shroud means for forming an active liquid chamber between said runner and impeller, said shroud means being provided with a mouth for receiving charging liquid directed into said active liquid chamber, means for centrifugally bleeding said active liquid chamber, and a source of charging liquid within said housing, the improvement comprising orifice defining means located within said housing at a position adjacent the mouth of said active liquid chamber, means for directing charging liquid from said liquid source to said orifice defining means to produce a flowing stream ofliquid aligned to enter said mouth, a splitter arm pivotally mounted within said housing to swing in a plane that extends across the flowing stream between the orifice defining means and the active liquid chamber mouth for deflecting a portion of the flowing stream away from the mouth, and control means for pivoting the splitter arm to vary the quantity of liquid entering the mouth of the active liquid chamber.

2. In a variable fill type liquid coupling as described in claim 1, said stream of charging liquid forming a shallow angle with the plane of said mouth so that said charging liquid is directed to the outer periphery of said active liquid chamber substantially without any deflection other than deflection in the rotary direction of movement of the coupling.

3. In a variable fill type liquid coupling as set forth in claim 2, saidd shroud means being provided with radially extending blades for intercepting said stream of charging liquid in order to give it a rotary component of motion before it reaches the outer periphery of said shroud means.

4. In a variable fill type liquid coupling as described in claim 1, said coupling further including an output shaft coupled to said driven runner for rotation about a common axis, said active liquid chamber mouth having an annular lip spaced from said output shaft in a plane perpendicular to said axis of rotation, said shroud means extending axially of the shaft from said mouth encompassing said driven runner, and said orifice defining means being aligned to direct the flowing stream of liquid into said mouth at a shallow angle with the plane perpendicular to the axis of rotation of the shaft so that liquid entering the mouth directly charges liquid held by centrifugal force in the outer circumferential portion of the active liquid chamber.

5. In a variable fill type liquid coupling as set forth in claim 4, said shroud means being provided with radially extending blades for intercepting said stream of charging liquid in order to give it a rotary component of motion.

6. In a variable fill type liquid coupling as described in claim 1, wherein the splitter arm is mounted for pivotal movement about an axis that extends in substantially the same vertical plane as the centerline of the orifice defining means and the centerline of the flowing stream ofliquid aligned to enter the active liquid chamber mouth.

7. In a variable fill type liquid coupling as described in claim 6, wherein said splitter arm comprises an angle-shaped vane having one leg extending in the plane transversely of the flowing stream between the active liquid chamber and the orifice defining means and another leg extending generally perpendicularly from said one leg towards the orifice defining means.

8. In a variable fill type liquid coupling as described in claim 6, wherein said splitter arm is provided with a lever arm extending laterally from the pivot axis thereof, and said control means includes a pressure responsive plunger mounted to bear upon the lever arm in a given direction, a compression spring mounted to bear upon the lever arm in a direction opposite to said given direction, and an adjusting screw having one end operatively engagingg the compression spring to regulate the compressive force therein.

9. In a variable fill type liquid coupling as described in claim 8, wherein said adjustment screw extends through said housing for manual adjustment thereof, said control means further including a stop plate threadably fitted upon said adjusting screw and arranged to bear against the compression spring so as to compress the spring between the stop plate and the lever arm, said stop plate having a notch therein offset from the location where the stop plate is threadably connected to the adjusting screw, and a guide rod extending from said housing through said notch in the stop plate to prevent the stop plate from turning with rotation of the adjusting screw. 

1. In a variable fill type liquid coupling having a housing, a driving impeller rotatably mounted in said housing, a driven runner rotatably mounted within said housing in liquid coupling relation with said impeller, shroud means for forming an active liquid chamber between said runner and impeller, said shroud means being provided with a mouth for receiving charging liquid directed into said active liquid chamber, means for centrifugally bleeding said active liquid chamber, and a source of charging liquid within said housing, the improvement comprising orifice defining means located within said housing at a position adjacent the mouth of said active liquid chamber, means for directing charging liquid from said liquid source to said orifice defining means to produce a flowing stream of liquid aligned to enter said mouth, a splitter arm pivotally mounted within said housing to swing in a plane that extends across the flowing stream between the orifice defining means and the active liquid chamber mouth for deflecting a portion of the flowing stream away from the mouth, and control means for pivoting the splitter arm to vary the quantity of liquid entering the mouth of the active liquid chamber.
 2. In a variable fill type liquid coupling as described in claim 1, said stream of charging liquid forming a shallow angle with the plane of said mouth so that said charging liquid is directed to the outer periphery of said active liquid chamber substantially without any deflection other than deflection in the rotary direction of movement of the coupling.
 3. In a variable fill type liquid coupling as set forth in claim 2, saidd shroud means being provided with radially extending blades for intercepting said stream of charging liquid in order to give it a rotary component of motion before it reaches the outer periphery of said shroud means.
 4. In a variable fill type liquid coupling as described in claim 1, said coupling further including an output shaft coupled to said driven runner for rotation about a common axis, said active liquid chamber mouth having an annular lip spaced from said output shaft in a plane perpendicular to said axis of rotation, said shroud means extending axially of the shaft from said mouth encompassing said driven runner, and said orifice defining means being aligned to direct the flowing stream of liquid into said mouth at a shallow angle with the plane perpendicular to the axis of rotation of the shaft so that liquid entering the mouth directly charges liquid held by centrifugal force in the outer circumferential portion of the active liquid chamber.
 5. In a variable fill type liquid coupling as set forth in claim 4, said shroud means being provided with radially extending blades for intercepting said stream of charging liquid in order to give it a rotary component of motion.
 6. In a variable fill type liquid coupling as described in claim 1, wherein the splitter arm is mounted for pivotal movement about an axis that extends in substantially the same vertical plane as the centerline of the orifice defining means and the centerline of the flowing stream of liquid aligned to enter the active liquid chamber mouth.
 7. In a variable fill type liquid coupling as described in claim 6, wherein said splitter arm comprises an angle-shaped vane having one leg extending in the plane transversely of the flowing stream between the active liquid chamber and the orifice defining means and another leg extending generally perpendicularly from said one leg towards the orifice defining means.
 8. In a variable fill type liquid coupling as described in claim 6, wherein said splitter arm is provided with a lever arm extending laterally from the pivot axis thereof, and said control means includes a pressure responsive plunger mounted to bear upon the lever arm in a given direction, a compression spring mounted to bear upon the lever arm in a direction opposite to said given direction, and an adjusting screw having one end operatively engagingg the compression spring to regulate the compressive force therein.
 9. In a variable fill type liquid coupling as described in claim 8, wherein said adjustment screw extends through said housing for manual adjustment thereof, said control means further including a stop plate threadably fitted upon said adjusting screw and arranged to bear against the compression spring so as to compress the spring between the stop plate and the lever arm, said stop plate having a notch therein offset from the location where tHe stop plate is threadably connected to the adjusting screw, and a guide rod extending from said housing through said notch in the stop plate to prevent the stop plate from turning with rotation of the adjusting screw. 